When one grow older the contribution for SA will increase and OA will decrease.
Yes, I'm with you so far...
So in a bull market you find it hard to invest as your OA shrink and SA go up.
I've just lost you. What also tends to happen as you age is that your income goes up as you progress in your career. (OK, not necessarily, and not necessarily in a straight line, but we're talking averages here.) Also what tends to happen is that your MA reaches the Basic Healthcare Sum and your SA the Full Retirement Sum, meaning the MA portion of your compulsory contributions bounces into your OA. And all of that means you
should be able to increase your monthly (or quarterly) savings/long-term investment flow as you age, other things being equal.
As far as whether it's a bull market or not, that doesn't depend on your age. Bull markets could start when you're age 23, 29, 34, 42, and 51 or when you're 26, 32, 48, and 54. You just don't know, and you won't really know except with hindsight.
Ideally SA 4% is very good but as I say always look for lobang that can beat the 4% since now your every month SA has much more monies.
Among the investment choices that the CPF Investment Scheme (SA) offers. There aren't many! I happen to agree with the consensus that you just take the 4.0% offer as-is, count it as part of your "bond/bond-like" allocation, and call it a day. I don't think it's worth using those particular dollars to chase something else.
My strategy for me I think it works becuz now I cannot top up my SA as reach limit. CPF count your SA investment also for which I find this out this year. I even write to CPF my CPF balance not show reach why block me from top up. They then reply me they also factor in my outside SA investment monies.
Yes, the Full Retirement Sum (and thus SA top up limit) is computed based on your SA balance
plus SA withdrawals for the CPFIS(SA).